July in Perth is the warmest month of the year. In July, the weather in Perth is typically warm. Average daily high temperature in July is about 16 degrees above zero. On average, Perth has 20 rainy, 4 sunny, 4 cloudy, and 3 partly cloudy days in July. The rains are usually moderate. July as well as January, February, April, and May is considered the most uncomfortable time to visit Perth.